1. Field of the Invention
The present invention relates to an image forming apparatus which adjusts image forming conditions based on a detected density of a patch image, and a control method for such an image forming apparatus.
2. Description of the Related Art
An image forming apparatus such as a printer, a copier machine and a facsimile machine utilizing electrophotographic technology, when needed, forms a small test image (patch image) having a predetermined image pattern, detects the image density of this image with a density sensor, and adjusts operation conditions of the respective portions of the apparatus (image forming conditions) in accordance with the result of the detection, so that a desired image quality is achieved stably.
For instance, in the case of the image forming apparatus described in Japanese Patent Application Laid-Open Gazette No. 2001-75318, warming up of the apparatus is executed immediately after the apparatus has been turned on or immediately after the apparatus has been released from a sleep mode. As this completes, density adjusting processing is carried out. During the density adjusting processing, optimal values of a charging bias and a developing bias, which serve as density control factors which influence the qualities of images, are calculated based on a detected density of a solid or halftone image formed as a patch image. With the charging bias and the developing bias set respectively to thus calculated optimal values, optimal image forming conditions are attained. As an image forming operation is executed under the image forming conditions optimized in this manner, an image is formed in a favorable and stable image quality.
Among image forming apparatuses of this type is such an image forming apparatus which outputs, when necessary, a status sheet for the purpose of notifying a user, an operator or someone who otherwise uses the apparatus of the state of the apparatus. The status sheet describes operation parameters for the respective portions of the apparatus, the result of self-diagnosis and the like,
When an operator so wishes, it is desirable that these apparatuses will skip the density adjusting processing. These are when the first print time needs be shortened or when a reduction of the amount of toner demanded by the density adjusting processing is desired, for instance. In the event that an image consisting only of letters, characters, lines and the like or a monochrome image is to be formed, precise density adjusting processing is not always necessary. Besides, there may be an instance that a status sheet mentioned above is wanted for the purpose of maintenance of an apparatus. However, the conventional image forming apparatus described above does not meet these demands.